Ultrafast visual detection of Streptococcus suis via HtpsC-targeted LAMP-CRISPR-Cas12a coupled with lateral flow...

This study describes a rapid, visual detection platform for Streptococcus suis, a significant zoonotic pathogen, by integrating loop-mediated isothermal amplification (LAMP) with CRISPR-Cas12a and a lateral flow immunochromatographic strip (LFIA) readout. Targeting the conserved HtpsC gene, specific LAMP primers and a PAM-compliant CrRNA were designed. Following isothermal amplification, the Cas12a/CrRNA complex recognizes the HtpsC amplicon, initiating target-specific cleavage and subsequent trans-cleavage of a dual-labeled ssDNA reporter (FAM-BIO), enabling visual detection on a LFIA; a design which reduces false positives. The optimized assay detected HtpsC-positive S. suis strains within 45 min and achieved a visual detection limit of 1.1 × 10² CFU/mL under laboratory conditions, with no cross-reactivity observed against the tested nontarget bacteria. In addition to pure-culture dilutions, the assay was further evaluated using spiked porcine blood samples and achieved similar detection performance, supporting its preliminary applicability in a complex biological matrix. Overall, this study provides an HtpsC-targeted visual detection workflow for screening of S. suis and is expected to be further applied to on-site rapid detection of clinical samples.